In a method for protecting electronic data, a data processing system (20, 20A, 20B) uses (a) a master electrocardiogram (ECG) identifier (44) for an authorized user of the system and (b) a secret chip key (26) for the system to encrypt data in the system. Also, before allowing the encrypted data to be decrypted, the system collects an ECG reading for a current user of the system and uses (a) the collected ECG reading for the current user and (b) at least one predetermined ECG identifier (EID) vector for the authorized user to determine whether the current user is the authorized user. In response to determining that the current user is the authorized user, the system uses the master ECG identifier (44) for the authorized user and the secret chip key (26) for the system to decrypt the data.